This composite shows what the suspect in a Dec. 17 sexual assault in Woodbridge may look like. (Courtesy Prince William County Police)

WASHINGTON – Prince William County Police are looking for a man posing as a cable company worker after he reportedly attacked a teenager in her home in Woodbridge.

The alleged sexual assault also has the county school system reminding students about safety.

A 15-year-old girl reported the assault just after 3 p.m. on Dec. 17 at her home in Echo Court near Godwin Middle School. According to the girl, a man knocked on her door, asking to speak with a person who didn’t live in the home and then left.

Soon after, the man returned and threatened the girl if she didn’t let him inside. Once inside, the man displayed a knife and forced her to a bedroom where he sexually assaulted her.

At some point, the victim screamed and kicked and the man fled. The girl then called police.

A police spokesperson says the girl’s 25-year-old sister was in the basement of the home but was unaware of what was happening.

Officers were unable to locate the suspect. He is described as a black male between 20 and 29 years old with a medium build. He was wearing a gray jacket, red shirt, black pants and black dress shoes.

Godwin Middle School’s principal is sending children home with a letter today informing parents of the incident and reminding children about safety away from school according to Prince William County School Spokesman Phil Kavits.

Kavits tells WTOP the letter isn’t supposed to alarm children but instead be a reminder about not opening doors to strangers and about when to call police.

Anyone with information should call Crime Solvers at 703-670-3700 or 1-866-411- TIPS.